In an interview with the Irish Independent newspaper on January 26, IE CEO Mr David Franks said the project, which is already being considered by the Department of Transport, would involve constructing a branch running west from a junction with the Dublin – Drogheda – Belfast line at Clongriffin. In a second phase, the line could be extended north to serve the suburb of Swords before continuing northeast to rejoin the Dublin – Belfast Line.

"We think it could be done for about €300m, but that's very rough and ready," says Franks, adding that the link could be completed within five years. Ridership is projected to be around 3 million passenger per year.

The economic viability of the link could be improved if it is decided to revive the the Dart Underground project, which was shelved in 2011, although IE says the proposals are not dependent on this happening.

Dublin Airport was used by more than 21.7 million passengers last year, an 8% increase compared with 2013.